What Is the Difference Between a Faceted Stone and a Cabochon

A 2-carat sapphire rough sits on a lapidary bench. Three different cutting decisions create three different values. Faceted: $800. Plain cabochon: $200. Star sapphire cabochon with centered asterism: $1,200.

The material hasn't changed. The price variation documents what happens when a cutter chooses how to handle light.

The Physical Difference: What Actually Distinguishes Them

A cabochon presents a smooth, domed surface. The top curves convexly. The base sits flat or slightly domed. No angular faces exist anywhere on the stone. Polish alone creates the surface finish.

A faceted stone displays multiple flat surfaces arranged at calculated angles. These facets typically number 31 to 73 depending on cutting style and complexity. Each face meets adjacent faces at precise angles determined by the gem's refractive index and the desired light performance.

The terminology reflects the manufacturing process. Cabochon derives from the French "caboche," meaning head, describing the rounded dome shape. Faceted refers to the flat faces ("facets") ground and polished onto the stone's surface.

How Light Behaves: The Physics Behind The Price

Walk into a jewelry store and faceted diamonds dominate the display cases. The stones flash with internal fire - spectral colors breaking apart as white light enters and exits through precisely angled faces. A sapphire cabochon in the same case reflects light from its surface but generates no internal brilliance.

The difference documents how refraction versus reflection works in practice.

When light enters a faceted stone, it passes through the crown (top portion), strikes the pavilion facets (bottom portion) at angles calculated to cause total internal reflection, and exits back through the crown. The pavilion acts as a mirror angled to bounce light toward the viewer's eye. Each facet redirects light at slightly different angles, creating the sparkle and fire faceted stones display.

Dispersion adds another layer. As light refracts through angled facets, different wavelengths separate slightly, producing the rainbow flashes called "fire." Diamond shows strong dispersion. Sapphire displays less. Quartz shows minimal fire. The facet angles determine how much dispersion becomes visible.

Cabochons operate differently. Light hits the domed surface and reflects directly back. No internal refraction occurs because the stone lacks angled faces to redirect light. The dome shape creates concentrated surface reflections rather than internal brilliance. Color appears more saturated because light passes through less distance of material before reflecting.

The critical angle matters for faceted stones. Each material has a specific angle below which light leaks out the bottom instead of reflecting internally. Sapphire's critical angle sits around 34.5 degrees. Diamond's critical angle is approximately 24.4 degrees. Faceted pavilion angles must exceed these values to achieve total internal reflection. Miss the angle and the stone develops a "window" - a see-through section where light escapes instead of reflecting.

Cabochons don't concern themselves with critical angles. Surface reflection works regardless of dome height or curve radius. This is one reason cabochon cutting is more forgiving for beginners than faceting.

The Equipment Reality: What Each Method Requires

A cabbing machine consists of six grinding wheels mounted on a horizontal shaft. Coarse wheels (80-280 grit) shape the stone. Medium wheels (600-1200 grit) smooth the surface. Fine wheels (3000-14000 grit) with foam backing polish to mirror finish. Water drips continuously onto spinning wheels. A beginner can produce a finished cabochon in under an hour.

The machine costs $400-800 for home equipment. Commercial models run $1,500-3,000. The process involves handholding the dopped stone against spinning wheels, maintaining consistent pressure and movement patterns to create even curves.

A faceting machine operates fundamentally differently. A flat lap rotates horizontally. A mechanical arm holds the stone at precise angles via an indexed dop stick holder. The index allows rotation to exact positions - 96 positions around the stone's axis is standard. Height adjustment controls how deep each facet cuts. Angle adjustment determines the pavilion and crown geometry.

Faceting machines cost $1,500-5,000 for capable hobbyist models. Professional equipment runs $5,000-15,000. The precision requirements explain the price difference. Angle repeatability needs to hold within 0.1 degrees. Height measurements require accuracy to thousandths of an inch. Index positions must align perfectly or facet meets fail.

"You can cab on a faceting machine, but you can't facet on a cabbing machine," summarizes the equipment hierarchy. A faceting machine's flat lap can grind cabochons by handholding the stone, though the process feels awkward compared to dedicated cabbing equipment. A cabbing machine's cylindrical wheels can't create the flat, precisely angled facets required for faceted cutting.

Time Investment: What The Clock Actually Shows

Cut a simple cabochon from start to polish: 30-60 minutes. The process involves grinding the rough to approximate shape (10-15 minutes), smoothing through progressive grits (15-20 minutes), and polishing to mirror finish (10-15 minutes). Experienced cabbers work faster. Beginners need longer. But a finished cab takes an hour or less.

Facet a stone with 57 facets: 4-12 hours minimum. A simple design with 31 facets might take 4-5 hours for a practiced cutter. Medium complexity designs (57-73 facets) require 6-8 hours. Complex fantasy cuts or large stones need 2+ days. Sapphire and other hard materials add time because grinding proceeds slower.

The time difference reflects process complexity. Cabbing involves continuous motion against spinning wheels - grind, smooth, polish, done. Faceting requires cutting each face individually. Set angle. Set index position. Grind facet to precise depth. Check meets with adjacent facets. Adjust if needed. Move to next facet. Repeat 31-73 times. Then polish each facet individually, which often takes as long as cutting.

Production cutting operations in Jaipur employ different economics. Workers cutting calibrated cabochons all day might complete 12-16 stones per shift. A faceted stone still takes hours even with production techniques. The time investment per stone explains part of the cabochon versus faceted pricing gap.

Material Requirements: What Determines The Choice

Transparent stones get faceted. Translucent or opaque stones become cabochons. This rule holds about 80% of the time.

Diamond, sapphire, ruby, emerald, spinel, topaz, tourmaline, aquamarine, tanzanite, and other transparent materials typically receive faceted cuts. The transparency allows internal light travel. Faceting maximizes what the transparency enables.

Turquoise, opal, jade, lapis lazuli, malachite, tiger's eye, agate, and jasper become cabochons. Opacity prevents internal light refraction. Faceting would accomplish nothing because light can't travel through the material. Surface reflection from a polished dome maximizes the visual impact opaque materials can produce.

The exceptions prove illuminating. Phenomenal stones break the transparency rule completely. Star sapphire and star ruby contain rutile needle inclusions aligned in three directions. Cut as a faceted stone, the needles create clouding that reduces value. Cut as a cabochon with proper orientation, the needles produce a six-rayed star effect worth significantly more than either faceted or plain cabochon versions.

Cat's eye chrysoberyl demonstrates the same principle. Parallel silk inclusions create chatoyancy - a sharp band of light moving across the dome when the stone rotates. The phenomenon only appears in cabochon form. Faceting destroys the effect entirely.

Black opal presents another exception. The material is translucent enough for faceting, but the play-of-color displays better through a domed surface. Cutters choose cabochon form to maximize the color flash value rather than create internal brilliance.

Mohs hardness influences cutting decisions too. Stones below 7 scratch more easily. Faceted cuts with sharp edges show wear faster on softer materials. The smooth dome of a cabochon hides scratches better than flat facet faces. Moonstone (6-6.5), opal (5.5-6.5), and turquoise (5-6) typically stay cabochon partly for durability reasons.

The Historical Development: How We Got Here

Before the 14th century, all gemstones became cabochons. The technology to cut and polish flat facets at precise angles didn't exist. Ancient Egyptian carnelian, Roman cameos, medieval turquoise - everything was shaped and polished smooth.

Cabochon cutting remained standard until European craftsmen discovered that diamond powder could grind other gemstones efficiently. The horizontal cutting wheel emerged in the 1400s. Lapidarists began experimenting with flat faces instead of domed surfaces.

The table cut appeared first - a single large flat face on top, smaller flat faces around the sides, flat bottom. Light performance improved compared to cabochons. The rose cut followed in the 1500s - flat bottom, triangular facets rising to a point. Still not optimized for brilliance, but moving toward understanding how angled faces affect light.

The old mine cut and old European cut emerged in the 1700s-1800s as cutters calculated better angle relationships. Marcel Tolkowsky published diamond cut calculations in 1919 that established the modern 57-facet brilliant cut standard. His mathematical analysis determined optimal crown angle (34.5 degrees), pavilion angle (40.75 degrees), and table size (53% of diameter) to maximize light return.

Faceting technology progressed faster than understanding. Even today, cutters sometimes choose faceted forms for materials better suited to cabochons, or vice versa, based on market preferences rather than optical properties.

Mid-century modern jewelry designers deliberately chose cabochon cuts for aesthetic reasons. Georg Jensen's silver work featured turquoise and moonstone cabochons. Scandinavian designers used amber and jasper cabs. The smooth domes complemented clean modern lines better than faceted sparkle. The design movement elevated cabochons from "lesser cut" to intentional choice.

The Market Decision: What Cutters Actually Do

A lapidary artist examines rough material and runs calculations. If cutting for maximum value, several factors determine which method to choose.

Transparency dominates. Can light pass through the material? Faceting becomes possible. Is the material opaque? Cabochon is the only option that makes sense.

Inclusions matter. Clean material with no visible flaws justifies faceting's time investment. Included material often cuts better as cabochons where the dome shape concentrates color and hides imperfections.

Size influences decisions. Smaller stones (under 1 carat) rarely justify faceting's time investment unless the material is valuable. A 0.5-carat garnet might take 4 hours to facet but sell for $20. The same time cutting ten cabochons generates more revenue. Large stones (over 5 carats) usually get faceted when transparency allows because the size displays faceted brilliance effectively.

Rough shape plays a role. Material that naturally forms oval or round shapes cuts efficiently into cabochons with minimal waste. Crystals with good geometric form cut efficiently into faceted stones aligned with the crystal structure.

The market itself creates feedback loops. Diamond engagement rings drive demand for faceted diamonds. Southwestern jewelry traditions drive demand for turquoise cabochons. Designer preferences for specific periods (Art Deco faceted pieces versus mid-century cabochons) influence what sells and therefore what cutters produce.

What This Means For Hand Cutting

Someone learning lapidary work faces a choice: which method to learn first? The conventional advice suggests starting with cabochons. The technique is more forgiving. Uneven grinding or missed polish spots remain visible but don't ruin the stone's function. A slightly asymmetric dome still looks acceptable.

Faceting demands precision from the first stone. Miss an angle by 2 degrees and meets fail. Cut one facet too deep and the entire tier looks uneven. Polish incompletely and scratches become obvious under magnification. The learning curve is steeper and mistakes cost more in ruined rough.

But faceting equipment enables both techniques. A person can cut cabochons on a faceting machine's flat lap with some adaptation. Learning faceting first provides access to both methods eventually.

The material cost matters too. Cabochon-grade rough costs less than facet-grade material. A beginner learning on $5 agate rough wastes less money than learning on $50 sapphire. Once skill develops, moving to better materials makes economic sense.

The time investment reflects different values. Cabbing provides quick results - satisfaction within an hour. Faceting requires patience - satisfaction after many hours. Some people prefer rapid completion. Others enjoy extended focus on single stones.

The Light Physics Remain Constant

Strip away equipment and technique and marketing preferences, and the physics persist. Faceted stones manipulate internal light refraction through precisely angled faces. Cabochons concentrate surface reflection through curved domes.

One isn't superior. They're different solutions to different problems. Transparent materials with no phenomenal effects display better faceted. Opaque materials and phenomenal stones display better as cabochons. Translucent materials could go either way depending on specific characteristics.

A faceted sapphire and a star sapphire cabochon cut from the same rough demonstrate the distinction. The faceted version shows brilliant internal sparkle. The cabochon version shows a centered six-ray star. Both are "correct" cuts for their intended effects. The star cab commands higher prices not because cabochons are better, but because the asterism phenomenon adds rarity value.

The equipment differences, time investments, and material requirements all flow from this fundamental choice: refract light internally or reflect light from the surface. Everything else is implementation detail.